Such switches are known in the prior art, but there is room for improvement. These switches must open and close a laser beam path with accuracy and without undesirable delay. Therefore, at the moment of activation, the control elements of conventional electromagnetic switches for opening and closing receive double the power received during normal continuous operation. Therefore, conventional switches of this type require so-called overload protection mechanisms, which increase the technical effort and expenditure. Another disadvantage resides in the fact that these protection means are an additional source of error and failure.
German Patent No. DE-3,031,908 C2 (Kazensky et al.) published on Mar. 11, 1982 discloses a beam switch wherein the filter means are operated by an electromagnet having a linearly moving armature which tilts an arm or arms carrying the filter means. Such switches are relatively slow and require the above mentioned over-load protection.
German Utility Model Publication No. DE-7,823,716 U1 and German Patent Publication No. B 26482 of July 16, 1943 disclose energizing circuits for electromagnets including RC-networks which make sure that after a certain time delay following switch-on the holding force of the magnet is reduced to a certain proportion of the initial holding force. Any use of such circuits for laser beam switches is not suggested in these references.